Do I need a firewall?

What is firewall? Firewall is a software which blocks intrusions to your PC from outside. Intruders are almost always malicious users which try to dig out some sensitive informations from your PC (credit card numbers, important documents...)


Are you behind NAT (router)? Because of the way NAT works you do not need a firewall when using routers, you are safe just the way you are... If you are interested in how NAT exactly keeps you safe take a look here

If your modem does not work in a router mode then you definitely need a firewall.

Unfortunately ZoneAlarm is no longer free for personal use, you can still download older versions of it which are free at: http://www.oldversion.com/program.php?n=zalarm

Alternatively you can use free comodo firewall which is also quite good.